The law says that interfering with play requires the player to touch the ball. Rashford didn't touch the ball so he hasn't interfered with play.
There's a better argument to be made that he interfered with an opponent, which includes "making an obvious action which clearly impacts on the ability of an opponent to play the ball."
However, even that's debatable. For instance Dermot Gallagher, who's just analyzed this on the channel I'm watching, says that in his judgment, neither of the outfield defenders had a chance of playing the ball, but he's not so sure about the keeper. So there's a debate to be had but it's not crystal clear one way or the other.
One thing is for certain though - Rashford did not interfere with play as the law defines it.